Ottawa shootings: What motivated the gunman?

Canadian authorities said Thursday that suspected Ottawa gunman Michael Joseph Zehaf-Bibeau acted alone, but they are still trying to figure out his motive.

A U.S. law enforcement official confirms to CBS News that this picture is believed to be Michael Zehaf-Bibeau, the alleged Ottawa shooter.

His mother described Zehaf-Bibeau, a recent convert to Islam with a history of drug problems, as being lost and someone "did not fit in."

Why did he kill a Canadian soldier and then storm the Parliament building?

Do the Ottawa shootings raise the risk of ISIS-inspired terrorist attacks within the United States?

CBS News Homeland Security correspondent Bob Orr and senior security contributor Michael Morell weigh in.